U.S. patent application number 10/534681 was filed with the patent office on 2006-01-12 for method for determining a position of a part in a stepped bore of a housing, and injector for fuel injecting fuel.
This patent application is currently assigned to Siemens Aktiengesellschaft. Invention is credited to Jurgen Dick, Willibald Schurz, Martin Simmet.
Application Number | 20060005388 10/534681 |
Document ID | / |
Family ID | 32730729 |
Filed Date | 2006-01-12 |
United States Patent
Application |
20060005388 |
Kind Code |
A1 |
Dick; Jurgen ; et
al. |
January 12, 2006 |
Method for determining a position of a part in a stepped bore of a
housing, and injector for fuel injecting fuel
Abstract
The invention relates to a method and an injector for
determining a position of a second part (10) inside a stepped
boring (6). This part should assume an exact distance (H) from a
first part (2). In order to determine the distance (H) between both
parts (2, 10), a collar (3) is firstly introduced into a second
boring (6b) of the stepped boring (6) until it rests upon a step
(16) of the stepped boring (6). Afterwards, a punch (4), together
with a touch probe (5), which is located inside a longitudinal
boring (d), is placed upon a lower annular surface (17) of the
collar (3) or on an underside (17a) of the first part (2), and the
collar (3) is compressed until the predetermined distance (H) is
obtained. The distance (H) is measured to a reference measure (x)
between a projecting end piece (E) of the touch probe (5) and a
reference mark (B) outside of the punch (4). The stamping process
is stopped once the reference measure (x) has been obtained.
Inventors: |
Dick; Jurgen; (Laaber,
DE) ; Schurz; Willibald; (Pielenhofen, DE) ;
Simmet; Martin; (Bad Abbach, DE) |
Correspondence
Address: |
LERNER AND GREENBERG, PA
P O BOX 2480
HOLLYWOOD
FL
33022-2480
US
|
Assignee: |
Siemens Aktiengesellschaft
|
Family ID: |
32730729 |
Appl. No.: |
10/534681 |
Filed: |
January 30, 2004 |
PCT Filed: |
January 30, 2004 |
PCT NO: |
PCT/EP04/00906 |
371 Date: |
May 12, 2005 |
Current U.S.
Class: |
29/890.124 ;
29/592.1; 29/602.1; 29/890.127 |
Current CPC
Class: |
F02M 2200/70 20130101;
Y10T 29/49417 20150115; F02M 61/188 20130101; F02M 47/027 20130101;
F02M 63/0026 20130101; F02M 61/168 20130101; Y10T 29/49412
20150115; Y10T 29/4902 20150115; F02M 63/0043 20130101; F02M
51/0603 20130101; F02M 63/004 20130101; Y10T 29/49002 20150115 |
Class at
Publication: |
029/890.124 ;
029/602.1; 029/592.1; 029/890.127 |
International
Class: |
H01S 4/00 20060101
H01S004/00; H01F 7/06 20060101 H01F007/06; B21D 51/16 20060101
B21D051/16; B21K 1/20 20060101 B21K001/20 |
Claims
1-10. (canceled)
11. A method for positioning a component in a housing, the method
comprising: providing a housing with a first bore having a first
diameter and a second bore having second diameter larger than the
first diameter, and a step formed between the first bore and the
second bore; fixing a first component with a lower side in the
first bore; inserting a coining ring into the second bore up to the
step; inserting a die with a first reference mark marked thereon
and a longitudinal bore formed therein into the second bore;
inserting a probe with a second reference mark into the
longitudinal bore until the probe contacts the first component;
establishing a reference measurement between the first and second
reference marks representing a distance between the lower annular
surface of the coining ring and the lower side of the first
component; compressing the coining ring with the die until the
reference measurement corresponds to a predefined value for the
distance; and placing the component in the second bore at the
distance.
12. The method according to claim 11, wherein the housing is an
injector housing.
13. The method according to claim 12, which further comprises
monitoring the reference measurement using a mechanical or optical
measuring device during compression of the coining ring.
14. The method according to claim 12, which further comprises
recording the reference measurement using an electrical measuring
device.
15. The method according to claim 12, wherein the component and the
first component are inserted into a stepped bore of a housing of a
fuel injector.
16. The method according to claim 12, wherein the first component
is configured as a piezo-electric actuator.
17. The method according to claim 16, wherein the first component
is configured as a base plate of the actuator.
18. An injector for fuel injection into an internal combustion
engine of a motor vehicle, the injector comprising: a housing
having a first bore with a first diameter and a second bore with
second diameter larger than the first diameter, and a step formed
between said first bore and said second bore, said step having a
step width; a first component fixedly disposed in said first bore;
a second component disposed in said second bore; and a coining ring
disposed to rest on said step, having an annular width and a height
stamped by a die to an exact predefined distance from said first
component, said annular width being wider than said step width for
creating an enlarged contact surface for an effective force between
said second component and said step.
19. The injector according to claim 18, wherein said contact
surface is smooth.
20. The injector according to claim 19, wherein said contact
surface at least one of polished and flat.
21. The injector according to claim 20, wherein said contact
surface is perpendicular to an axis of said bores.
22. The injector according to claim 18, wherein said second
component is a stroke inverter.
23. The injector according to claim 18, wherein said second
component is a nozzle body or an activation element of a
servo-valve.
Description
[0001] The invention is based on a method for determining the
position of a second component in a stepped bore of a housing, in
particular an injector housing, having two bores of two different
diameters, the second component in the second bore being intended
to be arranged at a predefined distance from a first component,
which is already fixed in the smaller first bore, and a ferrule
being inserted into the larger, second bore up to a step of the
stepped bore, which a die compresses until the predefined distance
from the first component is achieved and the second component then
being inserted up to the compressed ferrule, or an injector for
fuel injection according to the generic part of the independent
claims 1 and 7.
[0002] Injectors for fuel injection into an internal combustion
engine having a piezo-electric actuator as the drive unit in
particular have to be manufactured with maximum precision, as on
the one hand the change in the length of the actuator produced by a
voltage pulse is only of the order .mu.m and is therefore extremely
minimal. On the other hand the quantities of fuel to be injected
have to be precisely proportioned in order to optimize combustion
processes in the engine and to comply with the required emission
limits. To be able to satisfy these requirements, the individual
mechanical parts of the injector in particular must be manufactured
with maximum precision. Even linear measurements with strict
manufacturing tolerances can accumulate to produce unpermitted
errors.
[0003] Until now this problem was resolved by dimensioning the
individual components exactly and then introducing precisely
manufactured spacer rings into the bore to compensate for the
calculated measurement errors when positioning individual
components precisely in the injector. This method requires many
different spacer rings to be kept in stock. This procedure is
therefore very expensive and increases the manufacturing costs of
the injector significantly.
[0004] A method has also become known from DE 199 56 256 A1, in
which a ferrule is introduced into a stepped bore of an injector.
The ferrule is placed on the step at the transition between two
bores in the stepped bore. The ferrule is then compressed using a
stamping tool, until the required distanced from a first component
already fixed in the stepped bore is achieved. To be able to
control the stamping process, an electric sensor is integrated in
an insulated fashion at the tip of the die to supply a disconnect
signal to a drive unit of the die, as soon as contact is made with
the fixed first component. An unfavorable aspect of this appears to
be that the measuring point of the electric sensor at the tip of
the die is not visible during the compression process, as it is
inside the stepped bore and cannot be observed there. This can
result in control errors, if for example a dirt particle is
deposited on the sensor head and the sensor disconnects the drive
unit too early as a result. As there is practically no possibility
of control, this can easily result in an unidentified manufacturing
error.
[0005] The object of the invention is to locate the position of the
components to be integrated in the housing precisely in a housing,
in particular in an injector for fuel injection, at a predefined
distance in a stepped bore. The object also comprises providing an
improved injector. The object is achieved with the features of the
independent claims 1 and 7.
[0006] The method according to the invention for determining the
position of a second component in a stepped bore and the injector
with the characterizing features of the independent claims 1 and 7
in contrast have the advantage that the measuring point is outside
the bore and the distance from the component fixed in the bore can
be read using a probe, which creates a reference measurement
between the projecting end piece of the probe and a reference mark
on the die. It is thereby simple to control the measuring process
at any time, to improve manufacturing consistency. It is deemed
particularly advantageous that the stamping process can be observed
continuously so that an approximation to the reference measurement
can be observed and verified in a simple fashion.
[0007] The measures listed in the dependent claims result in
advantageous developments and improvements of the method specified
in the independent claims 1 and 7 or the injector. It is deemed
particularly advantageous that the reference measurement can be
greater by a predefined value than the predefined distance. This
advantageously means that after integration the two components are
at a certain distance from each other, which can be used as the
idle stroke for the actuator.
[0008] The reference measurement can be recorded in a particularly
simple fashion using a known mechanical or optical measuring device
such as a feeler gage, dial gage, eyepiece, camera, interference
method, etc. The measuring devices operate reliably and can also be
operated easily by untrained personnel.
[0009] After automatic series manufacture it appears particularly
favorable to record the reference measurement with an electrical
measuring device, for example a simple electric contact. It is
thereby particularly advantageous that the measuring process can be
automated, so that fewer qualified personnel are required and
manufacturing costs can be reduced.
[0010] A preferred and advantageous application of the method is
seen in the case of an injector for fuel injection, as in this
instance the distance between the components to be integrated in
the stepped bore of the injector housing has to be complied with to
a particularly high level of precision.
[0011] As its physical characteristics are such that a
piezo-electric actuator only changes very slightly in length,
compliance with the exact distance from a second component, for
example a servo-valve, a nozzle body, a deflection device, etc. is
particularly important, in order to be able to utilize the
available length change in the actuator as fully as possible.
[0012] In the case of the injector for fuel injection it is deemed
particularly advantageous that the ring width of the ferrule is
greater than the step width of the stepped bore. This results in a
better bearing surface for the second component, which can as a
result be positioned more securely and more precisely in the
stepped bore.
[0013] A smooth and in particular polished bearing surface of the
ferrule also appears to be advantageous for play-free positioning
of the second component. It would be very difficult and involve a
high level of extra cost to manufacture such a precise surface
directly on the step, as the step is located relatively deep inside
the bore and is therefore very difficult to reach with a tool.
[0014] A plurality of exemplary embodiments of the invention are
illustrated in the drawing and are described in more detail in the
description which follows.
[0015] FIG. 1A shows two exemplary embodiments of the invention
with an injector,
[0016] FIG. 1B shows an enlarged section of the injector housing
and
[0017] FIG. 2 shows a longitudinal section through an injector.
[0018] FIG. 1A shows a schematic illustration of a housing 1,
having a stepped bore 6 in the axial direction. The housing 1 can
quite generally be a unit, into which two components 2, 10 are to
be integrated at a predefined distance from each other exactly and
with low tolerances. In the preferred application according to the
invention an injector housing is used as the housing 1, into which
the two components 2 and 10 are to be integrated. The first
component 2 is for example an actuator, in particular a
piezo-electric actuator. A second component 10 is to be integrated
at a predefined distance H from the first component 2. The first
component 2 can however also be a base plate of the actuator,
etc.
[0019] The second component 10 is configured as a control element,
in particular it can be a stroke inverter, a nozzle body or an
activation element of a servo-valve, etc., which is to be activated
by the piezo-electric actuator 2.
[0020] Before the second component 10 can be integrated, the first
component 2 is first inserted into a first bore 6a of the stepped
bore 6 as exactly as possible in a place provided for this purpose
and fixed there. A lower side 17a of the first component 2 forms a
first reference surface for the predefined distance H. The first
bore 6a can be seen in the upper part of FIG. 1 and has a first
diameter d1, which is smaller than a second diameter d2 of a second
bore 6b. The second bore 6b is arranged in the lower part of the
stepped bore 6. An annular step 16 is formed at the transition
between the two bores 6a, 6b because of the different diameters d1,
d2.
[0021] In a next step a ferrule 3 is inserted into the second bore
6b with the larger diameter d2 until it rests on the annular step
16 of the stepped bore 6. The ferrule 3 is shaped such that it does
not impair the function of the second component 10 to be integrated
later.
[0022] The lower side 17a of the first component 2 fixed in the
first bore 6a therefore forms a reference base in respect of a
lower annular surface 17 of the ferrule 3 for a distance H, at
which the second component 10 is to be supported in the second bore
6b after the ferrule 3 has been stamped.
[0023] The height of the ferrule 3 is selected such that by
compressing the ferrule 3 the distance H, which is predefined as a
target measurement and is measured between the lower side 17a of
the first component 2 and the lower annular surface 17 of the
ferrule 3, can be manufactured to a predefined value.
[0024] Once the ferrule 3 has been placed on the step 16, a die 4
is introduced into the second bore 6b up to the lower annular
surface 17 of the ferrule 3. The die 4 has a central longitudinal
bore 18 with a diameter d, into which a probe 5 can be inserted
until its head end makes contact with the lower side 17a of the
first component 2. The length of the probe 5 is a function of the
measuring method used and is for example dimensioned such that an
end piece E of the probe 5 projects a small way out of the
longitudinal bore 18 of the die 4.
[0025] In order to be able to produce the required distance H by
stamping the ferrule, a first reference mark B is arranged on the
die 4, for example in the form of a flat measuring surface. A
second reference mark C is also marked on the end piece E of the
probe 5 and this too can be configured as a reference surface. A
reference measurement x can therefore be measured or read between
the first reference mark B on the die 4 and the second reference
mark C on the probe 5. The reference measurement x is thereby
selected such that, if the reference measurement x exists between
the first and second reference marks B, C, the lower annular
surface 17 of the ferrule 3 is the distance H from the lower side
17a of the first component 2.
[0026] In an alternative embodiment of the invention a marking or
scale 19 is marked on the end piece E, which can be used to monitor
the stamping depth or the distance between the lower side 17a of
the first component 2 and the lower annular surface 17 of the
ferrule 3.
[0027] A known stamping device (not shown) is now used to deform
the ferrule 3 to the extent that the predefined value x is achieved
for the reference measurement and therefore the distance H between
the lower annular surface of the ferrule 3 and the lower side 17a
of the first component 2. For this purpose the ferrule is for
example made from an appropriate cold-heading and cold-extruding
steel according to DIN 1654.
[0028] Alternatively there is also provision for the deformation of
the ferrule 3 to be terminated rather sooner. The stamping path is
somewhat shorter in this instance. A distance H+dx is therefore
set, to which a reference measurement with the value x-dx
corresponds. This is advantageous if for example the two components
2, 10 are to be integrated in a contactless manner at a certain
distance from each other. This results in an idle stroke with the
value dx for the actuator 2.
[0029] As the required reference measurement can be observed
continuously during the compression process, the compression
process can be stopped prematurely when the required distance H+dx
is achieved with the assembly measurement x-dx. The described
method allows the distance to be set to a precise value so that the
individual component tolerances can be compensated for effectively
and at low cost.
[0030] All mechanical, optical or electrical measuring arrangements
known per se can be used as the measuring device 7, with which the
reference measurement x or x-dx is recorded. In a preferred
embodiment for example an optical measuring device 7 of the LM
series from Heidehain GmbH is used, which is suitable for use in
particular in automation technology. This measuring device 7 has a
laser interferometric probe, with which measuring accuracies in the
nanometer range can be achieved. An He--Ne laser is used for
measuring, the light of which is supplied to a miniature
interferometer at the measuring point. The miniature interferometer
records the measuring movement of a measuring sleeve, corresponding
to the distance between the two reference marks B and C on the die
4 and the probe 5, and converts this movement to an optical
interference signal. The optical measuring signal is then
transmitted via an optical waveguide to an optical evaluation and
supply unit and output as a measuring result either on a digital
display or on the monitor of a computer. The measuring signal is
also used to control or disconnect the stamping device with the die
4, when the required distance H or H+dx or the reference
measurement x or x-dx has been achieved.
[0031] Alternatively an electric contact can be established between
the end piece E of the probe 5 and the die 4, said contact being
easy to see and adjust from outside. The electric contact is
thereby adjusted such that it supplies a disconnect signal to the
stamping device when the required reference measurement x or x-dx
is achieved. A section of such an electrical measuring arrangement
is illustrated schematically in the lower part of FIG. 1A. A
contact lug 31 is arranged on the die 4, with its contact oriented
towards the longitudinal bore 18. The height of the contact lug can
be adjusted and if necessary the idle stroke dx can be set using an
adjusting screw 31. The end piece E of the probe 5 in this instance
is rather shorter and is insulated from the die 4. When the ferrule
3 is being stamped, the die 4 moves upwards in relation to the
probe 5. The reference measurement x-dx is achieved when the
contact lug 31 comes into contact with the probe 5. The contact lug
31 thereby closes an electric circuit I across the probe 5 and the
die 4. This signal is then used to terminate the stamping
process.
[0032] FIG. 1B shows an enlarged representation of the stamping
process. It shows the ferrule 3, which is shaped by the stamping
process to the contour of the step 16 in the wall of the housing 1.
Use of the die 4 having a flat and smooth stamping surface, which
is also ground precisely at a 90.degree. angle to the longitudinal
axis, means that the stamped surface, i.e. the lower annular
surface 17 of the ferrule 3, is right-angled and smooth. As a
result the introduced second component 10 rests precisely and
without play on the ferrule 3, so that a predefined distance H or
H+dx or the predefined reference measurement x or x-dx can be
complied with exactly.
[0033] According to FIG. 1B the ferrule 3 preferably has an annular
width d3, which is greater than the width of the step 16, which has
a step width d4. The step 16 itself is not so favorable as a
bearing surface for the second component 10, as on the one hand its
step width d4 is relatively narrow and on the other hand its upper
surface has a certain roughness and irregularity due to the
machining tools. It may also be disadvantageous that the upper
surface can only be machined flat with difficulty due to the long
stepped bore 6.
[0034] Once the predefined reference measurement x-dx has been
achieved, the die 4 and probe 5 are removed from the second bore 6b
and the second component 10 is inserted until it rests on the lower
annular surface 17 of the compressed ferrule 3.
[0035] FIG. 2 shows a schematic illustration of a longitudinal
section through an injector for fuel injection for an internal
combustion engine of a motor vehicle. First it shows an injector
housing 1 with a stepped bore 6. The step 16 results from the two
bores 6a, 6b of the stepped bore 6 with their different diameters.
The ferrule 3 is placed on the step 16 and stamped to the required
thickness using the setting measurement 12. The first component 2,
a piezo-electric actuator, has been inserted into the smaller first
bore 6a and fixed to the housing 1 at the upper part of the housing
1 at a connection point A. The lower side 17a of the piezo-electric
actuator 2 has a predefined integration dimension 15 for the first
component 2, the actuator, in relation to the lower annular surface
17 of the ferrule 3. Together with the setting measurement 12 of
the ferrule, the predefined distance H is obtained from the two
measurements 15+12 as the measurement between the lower side 17a of
the actuator 2 and the lower annular surface 17 of the ferrule
3.
[0036] According to one exemplary embodiment of the invention, the
second component 10 is configured as a stroke transformer acting as
a stroke inverter. The stroke inverter rests without play on the
lower annular surface 17 of the ferrule 3 and its lower part moves
upward according to the arrows shown, when the actuator 2 extends
downward. When the actuator 2 is not activated, the stroke inverter
10 presses via a plunger 13 onto a servo-valve 20, so that said
valve closes. The servo-valve 20 regulates the fuel discharge from
a control chamber 21, which is supplied with fuel via a supply
valve. The control chamber 21 is limited by a nozzle needle 14 that
is supported in a movable manner. The fuel pressure pushes the
nozzle needle 14 onto a sealed seat 24. In this position the
injection holes 25 of the injection valve are closed, being
arranged behind the sealed seat of the servo-valve 20 when viewed
in the direction of flow. The nozzle needle 14 is arranged in the
control chamber 21, which is supplied via a supply line 22.
[0037] In the exemplary embodiment shown the stroke inverter 10
rests directly on the lower side 17a of the actuator 2. An idle
stroke can alternatively also be provided between the actuator 2
and the stroke inverter 10. If the actuator 2 is activated by
applying a voltage, the actuator 2 extends and presses onto the
stroke inverter 10. The stroke inverter moves the plunger 13 upward
so that the closing element of the servo-valve 20 lifts off the
sealed seat due to the action of the fuel pressure. This opens the
servo-valve 20 so that fuel flows out of the control chamber 21.
Fuel flows into the control chamber 21 at the same time via a
supply valve but the inflow is less than the outflow. The pressure
therefore drops in the control chamber 21. This relieves the load
on the nozzle needle 14. Fuel pressure acting on the pressure
surfaces of the nozzle needle 14 lifts the nozzle needle 14 off the
sealed seat 24. This opens the injection holes 25 and fuel is
injected into the combustion chamber of the engine. When the
current is discharged from the actuator, the servo-valve 20 closes,
the pressure in the control chamber 21 increases and the nozzle
needle 14 is pressed onto the sealed seat 24. This ends the
injection process.
* * * * *